2. Aspiration

Question 1

Define Aspiration

Answer 1

Aspiration is defined as the inhalation

oropharyngeal or gastric contents

into the lower airways.

Inhalation can lead to aspiration pneumonitis

and/or aspiration pneumonia.

The 4th National Audit Project (NAP 4),
published in 2011, found that

aspiration remained the leading cause
of airway-related anaesthetic deaths,

with most cases having
identifiable risk factors.

Question 2

Aspiration pneumonitis

Answer 2

Aspiration pneumonitis is an acute,
chemically induced inflammation
of the lung parenchyma

caused by the acid in the gastric contents.

The extent of the damage depends
on the

volume
and
acidity

of the material inhaled.

If the damage is severe
following this mechanism of lung injury,

it is called Mendelson’s syndrome,
and forms one of the diseases
on the ARDS spectrum.

Aspiration pneumonitis does
not necessarily lead to aspiration pneumonia,

and therefore antibiotic prophylaxis
has now fallen from favour
following simple aspiration.

Question 3

Aspiration Pneumonia

Answer 3

Aspiration pneumonia occurs

when superimposed infection
follows aspiration.

It is most commonly seen in patients
who suffer long-term ‘silent’ aspiration,
e.g. those with neurological problems
causing decreased airway protection.

However, it may occur following an acute aspiration

if the inhaled material is colonised
with upper airway flora

or in those patients with
bowel obstruction whose
gastric contents may be colonised with bacteria.

Question 4

What are the risk factors for

aspiration?

Answer 4

Factors that predispose to aspiration may be divided into patient factors and surgical factors.

Question 5

Patient factors:

Answer 5

Patient factors:

1 • 
Reduced level of consciousness – 
anaesthesia, 
intoxication, 
head injury

2
• Full stomach – 
recent meal, 
pain, 
trauma, 
opiates, 
bowel obstruction,
pregnancy, 
upper GI bleed

3
• Reduced barrier pressure – 
pregnancy, 
abdominal distension, 
hiatus hernia, 
obesity• 

4
Anatomy –
pharyngeal pouch,
oesophageal strictures.

Question 6

> Surgical factors:

Answer 6

• Operation –
gastrointestinal surgery

• Position –
lithotomy or head down

Question 7

How would you manage a case of intra-operative aspiration?

Pre Op

Answer 7

> Pre-operative: 
Management starts with prevention, 
and this begins with
identifying at-risk patients, 
followed by implementation of 
risk-reduction strategies:

• Administration of antacids –
e.g. ranitidine or sodium citrate

• Administration of prokinetic drugs –
e.g. metoclopramide

• Postponing anaesthesia for
6 hours following a meal

Question 8

How would you manage a case of intra-operative aspiration?

Peri Op

Answer 8

> Peri-operative:

• NG tube placement
and
aspiration of gastric
contents prior to surgery

• Use of rapid sequence induction
with cricoid pressure where appropriate

• Positioning the patient
head up where possible.

Question 9

> Management of aspiration:

Answer 9

1
• Call for help.

2
• Suction the airway.

3
• Administer 100% O2.

3
• If possible,
place patient in the left lateral position
with head down.

4
• Intubate if necessary.

5
• Suction down the ETT once
in situ before giving positive-pressure
ventilation, if possible.

6
Consider bronchoscopy and bronchial lavage

7
• CXR.

8
• Transfer to an appropriate bed, 
e.g. HDU or ITU, 
for supportive treatment – 
O2, bronchodilators and physiotherapy. 

9
In severe cases CPAP or
IPPV with PEEP
may be required post-operatively.

10
• Consider antibiotics.

11
Treatment with steroids has
not been shown to improve
outcome and so is not recommended.

Question 10

> Antibiotics:

Answer 10

Antibiotics should be considered
if any aspiration pneumonitis

does not resolve within 48 hours,

if the patient had bowel obstruction

or if they have been on regular antacids
as the resulting
increased pH allows
colonisation of the stomach.

Each hospital will have
its own antibiotic policy regarding aspiration,
and microbiology advice should be sought.

Question 11

> Starvation protocols:

Food
Clear Fluid

Breast milk

Bottle formula

Milk
Chewing gum

Answer 11

Patients should be fasted for the following times:
• Food: 6 hours
• Clear fluid: 2 hours
• Breast milk: 4 hours
• Bottle formula: 6 hours
• Milk: 6 hours
• Chewing gum: 2 hours

Clear fluid: if you are able to read the typed page through the fluid, it counts
as clear. More sugar-laden fluids such as cola count as food.